Trade unions, MPs and MEPs are to have their influence over Labour leadership elections reduced under plans announced by Ed Miliband.

It is part of the Labour leader's proposed shake-up of the party's historic relationship with the trade unions.

Mr Miliband said future leadership contests would be decided by a one member, one vote election.

He described the changes as some of the biggest in the party's history.

However, Conservative Party Chairman Grant Shapps said the changes would make it "even easier" for the "union barons" to pick the Labour leader in future.

'Cash shortage'

The Labour leader embarked on reforming the union link after a selection row in Falkirk last year when allegations of vote-rigging surfaced involving the Unite union.

No wrongdoing has been found to have taken place.

Mr Miliband said: "My reforms are about giving people from all walks of life a bigger say in the Labour Party so we can better tackle the issues that matter to them, like the cost of living crisis.

"Above all, I'm determined to change my party so we can change the country.

"This is about extending the principle of one member, one vote, the right principle for the 21st Century," he added.

"It's about saying we want to hear the voices of ordinary people, construction workers, shop workers, people from all walks of life."

He said there would be "financial consequences" for the party if the reforms went ahead.

"But when it's the right thing to do you should do it, and that's my principle," he added.

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Media captionConservative Party chairman Grant Shapps: "I do not think it is right to have trade union barons deciding policy"

"This is about my determination to make big change in our party and if you look at what Neil Kinnock, John Smith, Tony Blair, all of them wanted to extend this principle of one member, one vote."

Mr Miliband said the plans were about "a relationship more with individual trade unionists and less about the relationship with trade union leaders".

"Of course it's the case that trade unions themselves will continue to affiliate to the Labour Party, but it's about saying in the 21st Century, we do want to hear the voices of individuals."

Currently - under Labour's electoral college system - MPs and MEPs get a third of the votes to select a new leader, trade unions get a third and party members another third.

That system is to be abolished with every party member and those union members who donate to the party having an equal say.

Under Labour's plans, from the end of 2014 new members of unions affiliated to the party would have to opt in and pay a £3 fee to Labour before they got a vote.

This process would be phased in over five years for existing union members.

MPs would retain the sole right to nominate leadership candidates.

The threshold those candidates would need is also to be raised - possibly to 20% of Labour's MPs.

'Massive change'

The key changes

A new method of electing Labour's leader - the electoral college, which gives unions, party members and MPs/MEPs a third of the votes each, abolished in favour of one member, one vote

MPs have sole nomination rights for leadership candidates and those candidates will need a higher level of support than at present - possibly 20% of MPs

All union members will have to 'double opt-in' if they want to take part in a leadership contest. They have to say that they are content to give money to Labour AND that they want to become 'an affiliated supporter'

Only full party members - not trade-union 'affiliated supporters' - will choose parliamentary and council candidates

Changes to London mayoral selection - Labour's candidate to be selected in the same way as the party leader

New leadership rules will be put in place this year - but changes to the party's funding will be phased in over five years

At present, trade union members pay a levy to the party - decided by the union - unless they opt out.

Describing the changes as "massive", Mr Miliband acknowledged they could mean donations to the party falling.

"I make no apology for making sure the party is financially secure, so these reforms are being phased over a five-year timescale."

In another mooted change, registered supporters - those who have registered their support but are not full party members - would be entitled to vote in leadership and mayoral elections "for a small fee".

There are currently around 20,000 such supporters and the party hopes to boost that number - partly as a counterweight to the votes of trade unionists, BBC political correspondent Iain Watson said.

Mr Miliband sought to reassure his parliamentary party, telling the Guardian newspaper: "They will continue to play an important role with their right to nominate, so it will be MPs that will decide who goes forward to the election in the country on the principle of one member one vote."

The BBC also understands that unions will retain 50% of the votes at the party's conference.

Veteran Labour MP Alan Johnson said he had been arguing for the changes since his time as Communication Workers Union general secretary.

"This is absolutely the right way to go," he told BBC News.

"We have a genuine one member, one vote system to elect our leader."

But the party's Glasgow South West MP Ian Davidson said: "There's been nobody in my constituency coming along and saying to me at this time of economic crisis, what we need is a reorganisation of the Labour Party."

'Same old Labour'

Conservative party chairman Mr Shapps, however, suggested union members could outnumber ordinary members by 10 to one under the proposed changes.

He said: "Ed Miliband promised to loosen the trade union barons' grip on the Labour Party. But he has been too weak to deliver.

"Until now, the union barons could buy Labour's policies and pick Labour's leader. After these changes, it will be even easier for the union barons to buy Labour's policies and even easier to pick the leader."

He added: "Ed Miliband has shown he's too weak to stand up to the union barons who own him, too weak to stand up for hardworking people and too weak to offer a long-term economic plan to secure Britain's future."